The invention relates to a finish for partially oriented polyester yarn. More specifically, the invention relates to a finish which enables texturing of partially oriented polyester yarn with a minimum of fouling of texturing apparatus.
False twist texturing of partially oriented polyester yarns involves heating the yarn by means of a heater tube or plate, and subsequently twisting the yarn by means of a friction disc, belt or spindle. Lubricating finishes are typically applied to the yarn prior to the texturing operation in order to prevent filament breakage and other damage to the yarn during texturing.
Finish composition has been shown to be the cause of numerous problems encountered in texturing operations and is believed to be the cause of other problems. For example, excessive wear of polyurethane texturing discs and/or polyacrylonitrile/polybutadiene texturing belts can be attributed to impregnation of the finish into the disc or belt surface resulting in the softening and subsequent degradation of the surface. Excessive fuming or volatilazation of the finish during texturing results in liquid condensation and dripping onto various parts of the texturing apparatus, resulting in a poorly textured product and/or nonuniformity of dyeing in the subsequent dyeing operation. Dye uniformity is likewise adversely affected when any of various finish components migrate into the yarn during the heating operation. Non-volatile components of finishes have been found to deposit on the heater plate or tube resulting in a tar or coke buildup which can damage both yarn and heating elements. Still another problem is "snow" or particulate emission during texturing. Finish may be responsible for the amount of snow and/or for the quality of snow, i.e., dry vs. tacky.
Avoidance of the aforesaid problems can be particularly difficult since the precise causes of broken filaments, heater deposition, fuming, dye uptake variability and tacky snow are not precisely understood. Further, modifying a finish to avoid one problem frequently aggravates another problem. For example, a decrease in the amount of fuming can be accompanied by an increase in heater deposition and vice versa.
Each of the above problems typically result in the necessity for shutting down an active texturing operation in order to clean and/or repair the texturing apparatus. As such downtime represents an expense for the texturer, finishes are sought which can be used for several months without fouling or harming equipment.
Thus, to be commercially acceptable, a partially oriented yarn finish must lubricate and cling to the yarn while it is being twisted at extremely high speeds while not damaging equipment or yarn. The provision of a finish for a partially oriented polyester yarn thus presents a multifaceted undertaking.
It is an object of this invention to provide a finish for partially oriented polyester yarn which minimizes filament breakage during texturing.
Another object of the invention is to provide a finish for partially oriented polyester yarn wherein both fuming and heater plate deposition are minimized.
Still another object of the invention is to provide a partially oriented polyester yarn finish which obviates dye uptake variability in the polyester yarn.
A further object of the invention is to provide a partially oriented polyester yarn finish which effects little or no decomposition of texturing discs, belts or other friction texturing devices.
A still further object of the invention is the provision of a polyester yarn finish which can be used in a texturing operation for several months without shut down of texturing apparatus.